Methods for carrying out a topogram scan with a CT system using a cylindrical the curved multi-row detector and corresponding CT systems with program code for carrying out this method are generally known.
Such topogram scans mostly serve for planning recording of CT images. If multi-row detectors, i.e. detectors relatively wide in the system axis direction or also the z-direction are used for scanning a topogram, then multiple information at the same z-position in each case occurs during the scanning because of the wide radiation cone beam which is moved over the examination object—always related to the same beam angle in the circumferential direction, wherein however the rays which create this absorption information multiple times at the same z-position of the examination object do not always pass through the identical tissue, since they each have different angles of inclination. In practice however all absorption information which is measured at the same z-position of the examination object is used for imaging as if it penetrated identical voxels in the examination object and added them up overall for the image information.
In this way such topograms have the disadvantage that the images produced are unsharp and in addition that no overlay-free representation is undertaken and thus no depth information is also presented which would make possible a localization, of a lesion for example, in the depth.